class myThread(threading.Thread):  # 继承父类threading.Thread
   def __init__(self, threadID, name, counter):
      threading.Thread.__init__(self)
      self.threadID = threadID
      self.name = name
      self.counter = counter

   def run(self):  # 把要执行的代码写到run函数里面 线程在创建后会直接运行run函数
      print("Starting " + self.name)
      print_time(self.name, self.counter, 5)
      print("Exiting " + self.name)
